Clean ressources (#2615)

* rm docs/administration/img/admin_panel.png

Unused since #1920

* rm docs/content_management/img/access_focus_mode_PB.png

Never used since #2219

* rm docs/content_management/img/elements_toolbar.png

Not used since #2487

* rm docs/content_management/img/exit_focus_mode.png

Never used since #2219

* rm docs/content_management/images/img/fastly_variations.png

- …/images/img/… from #1864
- Duplicated to a better dir in #2487

* rm content_management/img/page_builder_….png

Several not used files from #2171

* rm docs/getting_started/img/ibexa_cloud_login.png

Never used from #2418

* rm docs/ibexa_products/img/ecommerce.png

Never used from #2460

* rm docs/pim/img/product_completeness.png

Not used anymore since #2232

* rm docs/pim/img/product_variants.png

Never used since #2138

(cherry picked from commit 21d66a4)

Author: adriendupuis

docs/administration/img/admin_panel.png

@@ -139,5 +139,4 @@ ibexa:
 You can select defined image variations during content item creation in the image options.
 Variations can include different sizing options and other filters that are applied to the image.
 
-![Fastly image variations](img/fastly_variations.png)
-
+![Fastly image variations](fastly_variations.png)